Valve Guide Wear

[Tim Glubaskas]

We are beginning to see excessive valve guide wear in cylinders

We have changed > 5 this summer for this wear - usually around half-time cylinders

Has anyone else been seeing this? We are finding it either during compression checks or during rocker inspections

[roger]

That's ugly. We haven't seen anything like that.

[navajoflyer]

I'm having the same problem. I've changed 3 cylinders in the last month all with bad guides. Now I have one of my airplanes with both engines using excessive amounts of oil. Pulled one cylinder and the guides were shot. Now we are going to top both engines at 1100 smoh. All these engines are lycoming factory overhauls. Additionally we notice that the last four engines we've purchased all seem to run hotter CHT than we normally see even though the fuel flows are where we've always run in the past. I'm wondering if Lycoming has made some production change that is causing this.

[roger]

Yeah, we had all 6 cylinders off the left engine at ~1300 hours since overhaul for the conn rod SB and nothing even close to that. We did have one that we removed for a suspected head crack (blowing blue) that was confirmed by NDT at 900 hours.

[Tim Glubaskas]

We just pulled a couple jugs for high oil consumption engine....yep, valve guides

Passed picture and issues up to Aero Recip.

Filed M or D (on sdr site) since this is gettin ridiculous


At least lycoming warranties em.......

[roger]

Oct 11, 2017 11:47:03 GMT -9 navajoflyer said:

Additionally we notice that the last four engines we've purchased all seem to run hotter CHT than we normally see even though the fuel flows are where we've always run in the past. I'm wondering if Lycoming has made some production change that is causing this.

I'm glad we're not the only ones!!! I went crazy with this most recent set of engines checking a re-checking timing, baffling, CHT indications, etc and finally concluded that this pair just runs hotter than our last couple.

[gsimmer]

I just purchased a PA31-325 with a Panther Conversion. I am told that the new cowls on the Panther Conversion should flow more air and ease the cooling issues. My engines have about 1200 hours on them since the conversion and I can not find where any of the cylinders have been replaced. I have checked the timing, replaced all baffle seals and replaced some the baffling that was cracked. On the left engine cylinders 3 and 6 run real hot and on the right engine cylinder 6 runs hot. What kind of temps are you seeing at what power settings?

[navajoflyer]

On our right engines we are seeing CHT of 440  on the #3 cylinder unless we leave the cowl flap open.  That's running 30" 2300 RPM and 20 GPH.  The left engines are running 420 - 425 on the #3 and #4 under the same conditions.  We never use to see CHT over 400 until we installed these last 4 engines. All of our engines are lycoming factory overhauls and installed with 100% new baffles and seals.

[gsimmer]

I just got back from the APS course in ADA and I have been trying different settings. Their magic number for temperature is a 380 degree target. Running ROP 31" 2300 RPM I need to be at 24GPH. Running LOP I have tried a few different settings. The last flight I ran at 33" 2400 RPM 13.5 GPH. According to the Auracle monitor this gave about 53 percent HP. At 9000 ft the best I could get is 168 kts TAS. I also have all new baffles and baffle seals. I checked the timing. My injectors are all matched from GAMI. GAMI has the same engine in their test cell and they are able to push the power up to 65 percent and 75 percent LOP without those cylinders going past 380 degrees. When I bought the plane last year, I borescoped the cylinders and I have a few valves that look like they got cooked pretty good and it looks like all of the exhaust seats are pitted pretty bad. The cylinders past a differential pressure test. I have to wonder if some of the heat is because maybe the valves are not sealing well are causing those cylinders to run hot. The rest of the cylinders are running in the 320 degree to 350 degree range. All of the cylinders have about 1200 hours on them while the case only has 500 hours on it. I have ordered 12 new cylinders and we are going to install them next month to see what happens. I showed my engine monitor graph to those at Gami and they were at a lost. The temps on those cylinders seem to oscillate up and down as well as the EGT trace but a 180 degrees out of phase with each other. Doesn't make sense